10691_Chao

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Anomalously warm conditions and their impact on marine ecosystem and seabirds during 20132015 off the U.S. west coast and in the Northeastern Pacific Ocean
Yi Chao1, John Farrara1 and Fei Chai2
1
Remote Sensing Solutions, Pasadena, CA, USA. E-mail: [email protected]
University of Maine, Orono, ME, USA
2
Anomalously warm waters during 2014 off the U.S. west coast are detected by two moorings at San
Diego and Monterey Bay, three gliders along the CalCOFI Line 67/80/90, and the hydrographic survey
off the coast of Newport, Oregon. The timing and strength of this 2014 warming is consistent and
concurrent at all these sites. A regional model simulation demonstrated that the remote forcing from
offshore lateral boundary conditions are the dominant contributor to this coastal warming. Both
observations and a Pacific Ocean ROMS model simulation show that this 2014 warming is correlated
with the anomalously warm waters offshore in the Northeastern Pacific Ocean (nicknamed ‘The Blob’)
with a time lag about 6-9 months. These warm waters were seen down to 100 meters and concurrent with
lower nutrient (e.g., nitrate) availability and reduction in primary production (e.g., lower phytoplankton
and zooplankton). Following the 2014 warm summer, a mass-mortality event of Cassin's auklet (a
planktivorous species) was observed off the U.S. west coast and Northeastern Pacific Ocean affecting
more than 100,000 birds. Large-scale warming off the U.S. west coast has been observed previously with
significant impact on the marine ecosystem and seabirds usually associated with major El Nino events
(e.g., 1982/83, 1997/98). However, the 2014 warming is unique and unprecedented both in terms of the
large geographic area covering both the ocean off the U.S. west coast and Northeastern Pacific Ocean
further offshore and the apparent link from the physical circulation to the marine ecosystem and seabird
population.
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